OK, so it is starting to happen again. Car is bone stock and had factory re-flash done about 4 months ago. After the car has been driving, if it is turned off then re-started 10 minutes later the idle will stumble back and forth between 100-1,000 RPM's before it smooths out to idle at 750 RPM. Car has done this twice in the last week, after it idles for a minute like this it smooth out without dying or re-start. Anyone have an ideas???

AA

 

my 08 lancer GTS does the same thing, I thought i might have a crack in my head gasket or something because my coolant is always low. I turn it on and it works fine but if i turn it off and turn it back on it shakes and idles very rough and sometimes the engine cuts off and i have to keep restarting it.

 

Why don't you try disconnecting the battery for 25 minutes and then connecting it back in?

That will reset the ECU and probably fix the idle issues.